1. Field of the Invention
The present invention is related to input/output (“I/O”) circuits and, more particularly, to methods and systems for sensing load conditions and for adjusting output current drive according to the sensed load conditions to maintain one or more signal characteristics within a desired range.
2. Background Art
Input/Output (“I/O”) circuits need to interface with different loads. Loads can vary from, for example, 50 pF-600 pF. Load variations can affect signal characteristics, such as rise and/or fall times. For example, loads with lower impedances tend to drain current faster from I/O circuits, which tends to decrease rise and fall times.
In many situations, signal characteristics, such as rise and/or fall times, need to be within a specified range. For example, certain interface standards, such as USB and PCI, require rise/fall times to be within a specified range.
What are needed are methods and systems for sensing load conditions and for adjusting output current drive as necessary to maintain one or more desired signal characteristics.